Presentation

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## Thigh muscle strength is not related to self-reported function in the medium to long term after anterior cruciate ligament reconstruction

.font70[**Michael Girdwood**, Adam Culvenor, Richard Johnston, Ben Mentiplay, Andrea Bruder, Danilo de Oliveira Silva, Tom West, Michael Hedger, Kay Crossley]

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.font70[SMA Conference 2022]

]

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### What we **don't** know:

- In the longer term - is muscle strength related to .red[self-reported function?]

- Is muscle strength more important for some people ?
  - e.g. athletic 
population 🏃‍
]

]

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## Research Question:

> - What is the relationship between thigh muscle strength and self-reported function at more than 2 years post ACLR?

> - Is this relationship different in a cohort who run regularly compared to those with ongoing symptoms

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## Methods - Participants

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.center[
.font150[n = 120] 
.font130[
Men and women post-ACLR 
Aged 18-50 & >2 years post surgery]
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#### Runners
- n = 33
- running ≥3x / week
- ≥10km / week

]

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#### Symptomatic Cohort

- n = 87
- 24-36 months post ACLR
- KOOS4 <80/100

]

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## Methods - Strength Assessment

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#### Peak isometric **quadriceps** (knee extension) and **hamstring** (knee flexion) torque
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<img src = "biodex.jpg", width = "90%">
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## Methods - Self-reported outcomes

#### Knee Osteoarthritis Outcome Score - KOOS 
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- Pain
- Symptoms
- Daily Living
- Sport & Recreation]
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- Quality of Life
- Patellofemoral
- KOOS4 - .font70[Average of Pain, Symptoms, Sport & Recreation, Quality of Life subcales]
]

#### Data-analysis
Beta-regression models modelled the relationship between muscle strength and self-reported function (KOOS subscales).

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## Results - The Population

| Measure |	Runners (n = 33) | Symptomatic (n = 87) |
|---------|--------------------|-----|
|Age (years)	| 32 (7) | 31 (6) | 
|% Female | 36% | 36% |
|BMI (kg/m2) | 23.8 (2.8)	| 27.9 (5.7) |
|Time since surgery (yrs)	| 9.2 (7.4) | 2.7 (0.3) |
|KOOS4 | 83.0 (15.9) | 65.6 (12.8) |
| Quadriceps Strength (Nm) | 207.5 (54.8) | 184.2 (59.7) |
| Hamstring Strength (Nm) | 97.4 (26.3) | 83.1 (29.0) |

- The runners had **.black[stronger]** quadriceps and hamstrings, and reported **.black[less symptoms]**.

- Time since surgery was not related to muscle strength.

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#### No meaningful relationships between .blue[thigh muscle strength] and .red[self-reported function]

.center[
<img src = "ameplot.png" width = 84%>

.font70[Findings 
were consistent for both runners and symptomatic cohorts (no interaction effect).]
]

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## Results

- **.black[Example:]** KOOS4 Subscale
 - **10 Nm greater** strength = **0.3% higher** KOOS4 .font90[(95%CI -0.3 to 0.9%)]

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<img src = "scatter.png">
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## Discussion

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- Our findings consistent with most existing literature >2 years post ACLR .font60[(Ericsson 2013; Flosadottir, 2016; Norte, 2018; Moller 2009). ]

- Psychological factors could contribute more to longer-term symptomatic outcomes .font60[(Filbay, 2021)]. 
 
]

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<img src = "discussion.png" >

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## Key Summary

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- .blue[Thigh muscle strength] was not associated with .red[self-reported function] in people >2 years post-surgery

- Findings were consistent in a group of runners and a lower functioning symptomatic cohort.

- Other non-physical factors may be more important to longer term knee health

]

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## Thank you!

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#### Questions:

.font80[
[m.girdwood@latrobe.edu.au](mailto:m.girdwood@latrobe.edu.au)

[@m_girdwood](https://twitter.com/m_girdwood)
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####Slides:

<img src = "qr.png" width = 25%> 
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